Prohibition has to stick (5)
I believe the answer is:
baton
'stick' is the definition.
(term for a stick or staff)
'prohibition has to' is the wordplay.
'prohibition' becomes 'ban' (ban is a kind of prohibition).
'has' indicates putting letters inside.
'ban' enclosing 'to' is 'BATON'.
(Other definitions for baton that I've seen before include "Policeman's truncheon" , "It's used by a conductor and a policeman" , "Staff" , "Police (or conductor's) stick" , "Conductor's wand" .)